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Nutritional diseases can still pose problems for companion avian species

Proper nutrition for companion avian species has long been and still is a central focus of avian veterinarians and aviculturists.

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While nutrient requirements have been precisely defined for "economically important" species such as poultry, the body of knowledge for companion species backed by scientific exploration is lacking in comparison.

Quite honestly, the exact nutritional requirements for companion psittacine species are still not known. However, we can still make educated estimates of their nutritional needs based on an understanding of the biology/ecology of their free-ranging conspecifics, basic biomedical sciences, information available regarding poultry nutrition and the most current concepts of companion avian nutrition.

Currently, high quality, state-of-the-art commercial diets are available for various age groups, activity levels, reproductive status and even birds with specific health issues such as liver or kidney disease. Unfortunately, just like many humans, birds do not always have the ability to choose a balanced diet if offered unhealthy items such as sour cream and onion potato chips or red-velvet cake. As a result, diseases related to inadequate or inappropriate diets are arguably still common occurrences. Therefore, this article will review selected nutritional diseases in avian species including their clinical signs, diagnosis and treatment.

Hypovitaminosis A

Vitamin A plays a crucial role in the health of avian species. It is necessary for vision, growth and differentiation of epithelial cells, immune function and normal function of secretory tissues.

Hyperkeratosis of the feet and gout may also occur. Clinical signs include white plaques, abscesses or focal kertinaceous granulomas in the oropharynx, blunting of chaoanal papillae, nasal discharge, periorbital swelling, dyspnea, polyuria, polydipsia, poor feather quality, feather picking and anorexia. Diagnosis is usually based upon dietary history, physical examination and cytology of the respiratory tract.

Treatment consists of the removal of plaques or abscesses, appropriate antimicrobial therapy and supplementation of vitamin A both parenterally (maximum 20,000 IU/kg IM) (Aquasol A, AstroZeneca LP, Wilmington, DE) and orally as needed. However, be careful not to over-supplement with vitamin A.)

Obesity

Obesity is another common nutritional disease of pet birds and is most often reported in budgerigars, Amazon parrots as well as rose-breasted and sulfur-crested cockatoos. Often, overindulgence in high-fat seed-based diets, or food items that are high in fat or energy (peanut butter, cheese or sweets) in conjunction with a sedentary lifestyle will lead to obesity.

Clinical signs include excessive deposition of fat or lipomas within the coelomic cavity as well as subcutaneous deposition along the neck, clavicular regions, breast area, body wall and abdomen.

Management of obesity requires either an increase in energy expenditure, a decrease in energy intake or both (most effective).Ideally, the bird should be placed on a pelleted diet (commercial diets with reduced calories are available) and given ample opportunity to increase its level of exercise.

Exercise may be gradually increased by allowing the bird more supervised activity out of the cage, providing toys that encourage playing as well as allowing the bird to fly so long as it is not dyspneic from its obesity. Thyroid hormone supplementation to reduce body fat is not recommended.

Lipomas may be carefully removed in those patients that do not respond to increased exercise or dietary modifications.

Hepatic lipidosis

Hepatic lipidosis is due to excessive deposition and storage of fat in the liver and is more frequently seen in budgerigars, cockatiels, Amazon parrots and cockatoos. Inactivity, toxic insult and malnutrition are the most common causes of hepatic lipidosis.

Ultimately, hepatic lipidosis results from an inability of the liver to mobilize fats deposited in the liver from the diet or from fats that are synthesized from carbohydrate or protein in the liver. The latter is the more important as mobilization of this fat requires the production of lipoproteins as the form of fat carried from the liver. Inadequate calories form protein metabolism, methionine deficiency, biotin and choline deficiency may inhibit formation of these lipoproteins, thereby inhibiting mobilization of fat and resulting in hepatic lipidosis.